The present invention provides devices, methods and kits for detecting analytes in biological samples. More particularly, the present invention provides means by which analytes requiring extraction from biological samples prior to detection may be extracted and detected in a single step.
Detection of analytes in biological samples has become an important aspect of medical practice. For example, identification and quantification of hormones in the blood can establish the diagnosis of many diseases, such as Cushing's disease or Syndrome of Inappropriate Antidiuretic Hormone. Also, recurrence of malignancies may often be determined by measurement of serum analytes such as carcinoembryonic antigen or prostate specific antigen. Generally, detection of such analytes requires complex instrumentation and assays are performed in reference laboratories.
Of particular value in clinical medicine is the detection of microbial pathogens in biological samples. As treatment may vary considerably depending upon the causative organism, accurate and rapid identification of pathogens in biological samples of patients suspected of having an infectious disease can be critical to provide prompt appropriate treatment to patients. Rapid identification of disease-causing organisms in biological samples is important even for non-life threatening infections. Traditionally, cultures were taken and empirical outpatient treatment begun. Often, patients receiving such empirical outpatient antibiotic treatment were lost to follow-up. This often occurs in syndromes such as pharyngitis or urethritis. After receiving antibiotics, the symptoms can improve even if the infectious organism is not eliminated. Therefore, as the symptoms improve the patient believes that they are cured while actually becoming chronically infected. Because the patient does not realize that they remain infected, they do not return to the physician for follow-up care based on the prior culture results. This may be detrimental to the patient as well as being a significant public health risk.
Traditionally, infectious diseases have been most commonly diagnosed by culture methods. Culturing microbial pathogens typically requires at least 24 hours to produce clinically relevant information. Rapid methods of diagnosing microbial infections have been developed to provide timely results for guiding clinical therapy. Some of the most effective of these rapid methods have been immunologically based. Monoclonal antibodies to microbe-specific antigens have been used to identify specific microbes in biological samples.
Group A Streptococcus in pharyngeal exudates can be identified by polyclonal or monoclonal antibodies to antigens specific for Group A Streptococcus. In their naturally occurring form, the Group A Streptococcus-specific antigens are not available for antibody binding and must be exposed prior to contacting with antibodies. This typically requires that the assay operator place the sample in acid and return later to transfer the acid solution to the assay medium. Multi-step assays such as these require more time and attention from health care personnel and thus are more expensive than one step assays.
Species-specific antigens of many other pathogenic organisms require pretreatment prior to detection. For example, Legionella pneumophila may be detected by non-serotype specific monoclonal antibodies after pretreatment with detergents and EDTA. Gosting et al., J. Clin. Microbiol., 20:1031-1035 (1984). Porin F protein antigens of another significant human pathogen, Pseudomonas aeruginosa, also require treatment by detergents and EDTA in order to be optimally detected by monoclonal antibodies in clinical samples. Counts et al., J. Clin. Microbiol., 26:1161-1165 (1988).
What is needed in the art are rapid means of detecting antigens which require pretreatment in biological samples. Preferably, these means are one step assays which minimize operator performance time. Quite surprisingly, the present invention fulfills these and other related needs.